Film bulk acoustic resonator

Abstract

Disclosed is a film bulk acoustic resonator (FBAR) including a substrate, a lower electrode formed above the substrate, a piezoelectric layer formed above the lower electrode, an upper electrode formed above the piezoelectric layer, and a first protection layer formed above the upper electrode. Here, the first protection layer covers the upper electrode while extending downward along a side surface of one end of the upper electrode to cover a certain area of the piezoelectric layer.

What is claimed is: 
     
       1. A film bulk acoustic resonator (FBAR) comprising:
 a substrate; 
 a lower electrode formed above the substrate; 
 a piezoelectric layer formed above the lower electrode; 
 an upper electrode formed above the piezoelectric layer; and 
 a first protection layer formed above the upper electrode, 
 wherein the first protection layer covers the upper electrode while extending downward along a side surface of one end of the upper electrode to cover a certain area of the piezoelectric layer, 
 wherein the first protection layer seals an air gap formed between a lower end of the one end of the upper electrode and the piezoelectric layer, 
 wherein the first protection layer has a layer thickness for covering the piezoelectric layer which is at least greater than a gap height of the air gap, and 
 wherein the FBAR further includes a second protection layer formed between the first protection layer and the upper electrode, and the second protection layer covers the upper electrode. 
 
     
     
       2. The FBAR of  claim 1 , wherein the first protection layer includes one or more dielectric materials of SiO x  and SiN x  (here, x is a positive real number greater than 0). 
     
     
       3. The FBAR of  claim 1 , wherein the second protection layer includes one or more dielectric materials of AlN x , SiO x , and SiN x  (here, x is a positive real number greater than 0).